Saturday, January 19, 2008

Technology Challenges: Buildings and Housing

Building anything in Antarctica is difficult. The lack of conventional resources such as timber and the remoteness of the continent alone make traditional construction a challenge. This post aims to outline alternative methods of construction that may produce buildings suitable for an Antarctic colony.

Most of the structures built in Antarctica today are not well enough designed to serve a permanent colony. One fundamental flaw is they are built above ground and thus are subject to the forces of the wind and extreme cold. In addition to this most structures leak out heat through windows and doorways further increasing the energy required to heat them.

Building Underground

The easiest way to combat this would be to build structures underground. The permafrost in Antarctica would provide a temperature stable environment year round. I have been unable to locate reliable sub-surface temperate data for Antarctic permafrost at various depths. So, for the following example I will use estimates. If anyone has that temperature data please send it in or post it in the comments section here.

Note the following estimate is given in Fahrenheit.

As a rough example:

If you build below ground and your sub-surface temperate is a stable 25 degrees, and you heat your buildings to 65 degrees you have a constant temperate differential of 40 degrees to maintain. Now, if you build above ground and the outside air temperature is -50 degrees, and you heat your buildings to 65 degrees you have a temperate differential of 115 degrees. It's fairly easy to tell that the 40 degree temperate differential is going to take far less energy to overcome than the 115 degree differential.

Reducing Heat Loss

One of the most important ways to reduce heat loss would be to build extremely well insulted structures. The use of commercially available insulting materials like the Thermalkool radiant barrier (which is paper thin and is rated R52) and other materials like mylar would help greatly. Using these materials in alternating layers with air pockets between it may be possible to build walls rated over R300 that are less than one foot thick. For comparison, the typical American home uses fiberglass insulation that's usually rated R30.

Another way to further reduce heat loss would be to seal the buildings air tight. Preventing air and with it heat from escaping the structure would reduce the energy demands needed to heat it. This of course presents an additional problem of maintaining a constant fresh air supply. For this an air exchanger system combined with a thermal energy recovery system via the use of Stirling engines or another thermal energy conversion technology could be used.

One example of such a system would be to have the cold fresh air intake shaft and the warm air exhaust shaft run parallel to each other with a number of Stirling engines sandwiched in between them. The temperature difference between the cold outside air and the warm air from inside the buildings could be converted back into electrical power this way. Also, a small amount of the waste heat would be transfered though the plates on the Stirling engines providing a small warming effect for the incoming air. This method could also be used with large chambers to effect a single large air mass at one time rather than a shaft system. A chambered system may also allow for multiple stages of thermal energy recovery and air intake heating to occur further increasing the energy efficiency of the system. Of course the larger and more complex the system the more it would cost to build and maintain.

Digging in Antarctica

Permafrost is notoriously difficult to dig through. However, with the use of explosives and modern tunneling techniques, that should be fairly easy to overcome. It will likely be far more expensive to build any sort of tunnel or underground structure in Antarctica compared with the rest of the world, but building any structure in Antarctica is already more costly than elsewhere.

If the underground structures are well insulated as described above, that will enable the surrounding ground to remain frozen. This will serve to increase the stability of the structures and tunnels requiring less bracing and support.

Natural Caves

There are a number of natural caves in Antarctica. There have even been accounts of stranded sailers surviving winters in caves on the sub-Antarctic islands. Many of those caves, especially on the continent have yet to be explored. Many more are buried and hidden under hundreds of feet of ice. It is possible there are caves large enough to build a colony inside them. Unfortunately, the odds of a large natural cave being in an accessible location suitable for a colony are slim to none. This does not mean the exploration of natural caves should be completely ruled out. It may be possible to enlarge a small natural cave to suit a colony. Tunnels between various smaller caves could in theory be dug to connect them. This would largely depend on the area to be colonized and features of the surrounding ground.

11 comments:

It would make a lot more sense to use heat exchangers than Stirling engines.

Also, since it takes a long time for heat to propagate very long distances through the ground, insulating underground buildings will not likely be sufficient to keep the surrounding ground frozen in the long run. You could pump air from outside through it to keep it frozen, though.

If a thermal exchanger was operating at less than 10% efficiency it may make more sense to covert that waste heat into electrical power. Some regenerative heat exchangers have efficiencies of over 95%, but to my knowledge most of those systems use fluids in a closed cycle system which may not work in the Antarctic environment. It is definitely a key issue that will need to be addressed in more detail. Power recovery via Stirling engines is only one option.

Also, any thawed ground could easily be refrozen by shutting off the heat to that section for a period of time. If it was planned properly a colony could shut down sections on a rotating basis and preform maintenance tasks or additional construction during the shutdown periods as well.

Building and testing various designs of thermal exchangers in Antarctica would probably give the most accurate picture of what works the best. A lot of things work well in theory or on paper but in actual practice may not be very effective or achieve nearly as high an efficiency.

Actually if you read my above comment again I was agreeing with you. The 95% efficiency was in regards to regenerative heat exchangers not heat engines. You are right on that point.

Also, do you think 9 months would be a long enough time to refreeze a layer of thawed permafrost? Since like most Antarctic bases I would assume there would be far more people visiting in the summer months, a good deal of the colony could be shut down in the winter to save power and help refreeze the surrounding ground. Of course this would only be an issue if the colony is built in frozen soil. If the buildings were built in solid rock thawing would not be an issue at all, it might even be beneficial.

Thank you for your comments Simon. You have been both insightful and stimulating.

How many people do you think could live in Antarctica? Antarctica is 9.2% of the earths land mass, and it gets about 42% the sunlight that the rest of the Earth gets, therefore, if the people lived in domed cities, perhaps 3.8% of the worlds population could live there. That would make it the 4th largest country in the world.

I did some calculations, if my figures above are true, then then Antarctic Colonies would provide an enormous advantage to the countries that have official territorial claims there. The countries are, France, Chile, Argentina, Australia, the UK, Norway and New Zealand. On average, these countries would more than DOUBLE their populations with their territories in Antarctica. France could fit 12% of its population in its antarctic territory, and Norway could put 956% its population in its antarctic territory.

These would also provide an enormous benefit to the rest of the world, due to Norway's enormous potential expansion, the amount of Norwegian Black Metal produced would increase TENFOLD, especially since Antarctica is the darkest and most brutal continent.